Heretofore there have been various types of metal preheat conveyors provided and a number of these constructions are in some relatively widespread commercial use today. Such prior structures are evidenced by my own prior U.S. Pat. Nos. 3,721,519 and 3,813,209. In these metal preheat conveyors, there sometimes have been difficulties with the supply of sufficient air to the bottom portion of the material being preheated as to insure its complete cleansing by oxidation of impurities on the surfaces of the scrap metal. My prior U.S. Pat. No. 4,135,702 provides one method and apparatus for preheating scrap utilizing a supply of auxiliary air to the materials in the lower portion of the preheat conveyor.
Naturally, it is desirable to preheat the scrap metal or other metals as rapidly as possible, and it also is very desirable to clean off or burn off any and all combustible materials on the scrap so that the supply of secondary air, or combustion air, to the materials in the lower part of the preheat conveyor is an essential factor to be considered in the design of metal scrap preheat conveyors.
The present apparatus is of the type shown in my above-identified patents and it also utilizes a scrap preheat conveyor generally as shown in my companion co-pending application Ser. No. 100,966, filed Dec. 6, 1979, which shows a desirable construction for securing the different sections of the scrap preheat conveyor to a support mechanism.